Ignacio Canepa T, Partner-Owner of Trio Riego.
Over the years, through experience and studies, it has been possible to determine that the most important aspect for agricultural production is water. During the last decade, this vital element has decreased considerably due to a prolonged drought that today affects the entire surface of Chile; due to this, it is essential to know how, and how much we are watering. Within the background that a farmer must be clear about is how much water his equipment delivers, for which there are many tools that allow measuring soil moisture, moisture tension, water movement in the plant, etc.
But if we do not know what our equipment should actually deliver and if it is actually delivering it, we will start with a very poor foundation to be able to use this type of more sophisticated or detailed tools, which is why we must initially know how many millimeters our equipment delivers, for which, initially, we must know how to obtain the instantaneous precipitation of our technical irrigation equipment.
One of the most common mistakes in the fields is to determine irrigation hours based on what we already have or on the experience of someone we know; but, normally, we do not notice if there are variations in the distance between rows or in the distance of the drippers or the flow of the latter.
We will try to explain in an easy and practical way the basic parameters that will allow us to have knowledge of the capacities and differences of our technological irrigation systems, this with formulas that are very simple to apply.
1.- Instantaneous precipitation of our system (mm/hour)
Example, cherry trees planted at 4.0 x 2.0 m with a double-line drip irrigation system, with 2.1 l/h drippers spaced 0.4 m (40 cm) apart:
That is, in this simple example, for every hour of irrigation our equipment is able to apply 2.62 mm of water per hectare, this is equivalent to 26.2 m3 per hour per hectare.
2.– Capacity of my irrigation equipment (mm/day): To make this calculation, we consider how many millimeters my irrigation equipment can apply daily by watering all sectors on the same day, regardless of the frequency or method of watering each field.
Number of sectors in my team
Example, following the same data already mentioned in point 1.- we will add that our equipment is designed with 6 irrigation sectors
If I wanted to calculate the capacity of my equipment in less hours, for example 22 hours, it is as simple as modifying the hours in the previous equation.
If I wanted to calculate how many millimeters I applied when I determined a certain number of hours, we just have to multiply the instantaneous rainfall by the hours watered; in our example, if I watered for 12 hours it would be:
3.- Water supply (m3/hol/sec),How much water should we have in our field to supply the water requirements of our irrigation equipment?
Example, following the same data above, assuming that it is a 24 ha field and assuming that one sector has 4.3 ha
To transform from m3/hal/sec you just have to divide by 3.6 (this is because 1 m3 is equivalent to 1,000 liters and 1 hour is equivalent to 3,600 seconds).
Once you have this information clear, your second step will be to check if your irrigation equipment is actually delivering the flow rate for which it was designed.
